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New CentOS Atomic Release and Kubernetes System Containers Now Available

Last week, the CentOS Atomic SIG released an updated version
(<a href="https://wiki.centos.org/SpecialInterestGroup/Atomic/Download" title="https://wiki.centos.org/SpecialInterestGroup/Atomic/Download">https://wiki.centos.org/SpecialInterestGroup/Atomic/Download</a>) of
CentOS Atomic Host (7.1707), a lean operating system designed to run
Docker containers, built from standard CentOS 7 RPMs, and tracking the
component versions included in Red Hat Enterprise Linux Atomic Host.

The release, which came as part of the monthly CentOS release stream,
was a modest one, including only a single glibc bugfix update
(<a href="https://lists.centos.org/pipermail/centos-announce/2017-July/022505.html" title="https://lists.centos.org/pipermail/centos-announce/2017-July/022505.html">https://lists.centos.org/pipermail/centos-announce/2017-July/022505.html</a>).
The next Atomic Host release will be based on the RHEL 7.4 source code
(<a href="https://seven.centos.org/2017/08/centos-linux-7-1708-based-on-rhel-7-4-source-code/" title="https://seven.centos.org/2017/08/centos-linux-7-1708-based-on-rhel-7-4-source-code/">https://seven.centos.org/2017/08/centos-linux-7-1708-based-on-rhel-7-4-s...</a>)
and will include support for overlayfs container storage, among other
enhancements.

Outside of the Atomic Host itself, the SIG has updated its Kubernetes
container images to be usable as system containers
(<a href="http://www.projectatomic.io/blog/2016/09/intro-to-system-containers/" title="http://www.projectatomic.io/blog/2016/09/intro-to-system-containers/">http://www.projectatomic.io/blog/2016/09/intro-to-system-containers/</a>).
What's more, in addition to the Kubernetes 1.5.x-based containers that
derive from RHEL, the Atomic SIG is now producing packages and
containers that provide the current 1.7.x version of Kubernetes.

## Containerized Master

The downstream release of CentOS Atomic Host ships without the
kubernetes-master package built into the image. You can install the
master kubernetes components (apiserver, scheduler, and
controller-manager) as system containers, using the following
commands:

The CentOS Virt SIG is now producing Kubernetes 1.7.x rpms, available
through this yum repo
(<a href="https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/master/virt7-container-common-candidate.repo" title="https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/master/virt7-container-common-candidate.repo">https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/...</a>).
The Atomic SIG is maintaining system containers based on these rpms
that can be installed as as follows:

Both the 1.5.x and 1.7.x sets of containers have been tested with the
kubernetes ansible scripts
(<a href="https://github.com/kubernetes/contrib/tree/master/ansible" title="https://github.com/kubernetes/contrib/tree/master/ansible">https://github.com/kubernetes/contrib/tree/master/ansible</a>) provided
in the upstream contrib repository, and function as drop-in
replacements for the installed rpms. If you prefer to run Kubernetes
from installed rpms, you can layer the master components onto your
Atomic Host image using rpm-ostree package layering with the command:
`atomic host install kubernetes-master`.

The containers referenced in these systemd service files are built in
and hosted from the CentOS Community Container Pipeline
(<a href="https://wiki.centos.org/ContainerPipeline" title="https://wiki.centos.org/ContainerPipeline">https://wiki.centos.org/ContainerPipeline</a>), based on Dockerfiles from
the CentOS-Dockerfiles repository
(<a href="https://github.com/CentOS/CentOS-Dockerfiles/tree/master/kubernetes" title="https://github.com/CentOS/CentOS-Dockerfiles/tree/master/kubernetes">https://github.com/CentOS/CentOS-Dockerfiles/tree/master/kubernetes</a>).

## Download CentOS Atomic Host

CentOS Atomic Host is available as a VirtualBox or libvirt-formatted
Vagrant box, or as an installable ISO, qcow2 or Amazon Machine image.
For links to media, see the CentOS wiki
(<a href="https://wiki.centos.org/SpecialInterestGroup/Atomic/Download" title="https://wiki.centos.org/SpecialInterestGroup/Atomic/Download">https://wiki.centos.org/SpecialInterestGroup/Atomic/Download</a>).

## Upgrading

If you're running a previous version of CentOS Atomic Host, you can
upgrade to the current image by running the following command:

$ sudo atomic host upgrade

## Release Cycle

The CentOS Atomic Host image follows the upstream Red Hat Enterprise
Linux Atomic Host cadence. After sources are released, they're rebuilt
and included in new images. After the images are tested by the SIG and
deemed ready, we announce them.

## Getting Involved

CentOS Atomic Host is produced by the CentOS Atomic SIG
(<a href="http://wiki.centos.org/SpecialInterestGroup/Atomic" title="http://wiki.centos.org/SpecialInterestGroup/Atomic">http://wiki.centos.org/SpecialInterestGroup/Atomic</a>), based on
upstream work from Project Atomic (<a href="http://www.projectatomic.io/" title="http://www.projectatomic.io/">http://www.projectatomic.io/</a>). If
you'd like to work on testing images, help with packaging,
documentation -- join us!

The SIG meets weekly on Thursdays at 16:00 UTC in the #centos-devel
channel, and you'll often find us in #atomic and/or #centos-devel if
you have questions. You can also join the atomic-devel
(<a href="https://lists.projectatomic.io/mailman/listinfo/atomic-devel" title="https://lists.projectatomic.io/mailman/listinfo/atomic-devel">https://lists.projectatomic.io/mailman/listinfo/atomic-devel</a>) mailing
list if you'd like to discuss the direction of Project Atomic, its
components, or have other questions.

## Getting Help

If you run into any problems with the images or components, feel free
to ask on the centos-devel
(<a href="http://lists.centos.org/mailman/listinfo/centos-devel" title="http://lists.centos.org/mailman/listinfo/centos-devel">http://lists.centos.org/mailman/listinfo/centos-devel</a>) mailing list.

Have questions about using Atomic? See the atomic
(<a href="https://lists.projectatomic.io/mailman/listinfo/atomic" title="https://lists.projectatomic.io/mailman/listinfo/atomic">https://lists.projectatomic.io/mailman/listinfo/atomic</a>) mailing list
or find us in the #atomic channel on Freenode.

This is probably a better one to use:
<a href="https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/node/virt7-container-common-candidate.repo" title="https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/node/virt7-container-common-candidate.repo">https://github.com/CentOS/CentOS-Dockerfiles/blob/master/kubernetes-sig/...</a>

It includes a line: "exclude=docker" to stick with the non-sig version
of docker.